Posts Tagged Tools

3D Printering

Ok, confession time.  I succumbed to the 3D printing fad thing.  I know.  I made fun of 3D printer fanbois in the past, but we got one at work.  Using it for a bit forced me to realize that they’re actually pretty cool.

My kit of reprap parts!

My kit of reprap parts!

I asked my whole family to chip in for a RepRap Prusa i3 kit for my birthday (in September, to give you an idea of how behind I am).  It came relatively quickly, but there were certainly some issues.  For one, everything smelled –very strongly– of cigarette smoke.  Luckily, it was mostly isolated to the outside of the packaging.  Once I unpacked everything, it went away.

Aaaarg! Two sets of threaded rods!

Aaaarg! Two sets of threaded rods!

Then, I discovered that I got two sets of threaded rods!!  That wouldn’t be so bad, except that I didn’t get any smooth rods!  I emailed the company, and they got a replacement set of smooth rods in the mail right away, but I still had to wait a while.  In the mean time, I figured that 5/16″ is awfully close to 8mm.  I bought some 5/16″ stainless steel rods from the hardware store to keep working on the printer.  The 5/16″ rods are undersized for the LM8UU linear bearings (they’re designed for 8mm rods), so there was extra slop in all the axes.  Eventually, the 8mm rods came in the mail, and I installed them.

There were a few other minor issues.  For one, the melamine material that was used for the main frame was thicker than the laser-cut slots.  I had to carefully trim the tabs so that they would fit.  It may be difficult to understand what I’m talking about without photos, but all that’s important to understand is that there were some attention to detail issues.

After printing for a while, I noticed another problem with the melamine.  It’s also used in the frame that holds the build platform to the Y axis bearings.  The frame material wasn’t strong enough to level the platform.  When I lengthened the screws on the low sides, the frame would just bend downward rather than moving the platform.  I found a place in town that sold me a sheet of 3/16″x1’x2′ aluminum for $5, from which I cut out a replacement frame with my scroll saw.

Other than those problems, everything went together smoothly.  One interesting thing about RepRaps (the models that I know about, anyway) is that they don’t really include something to hold your spool on.  I almost think it’s to give people something to design and print out of the chute.  My solution was to build a frame using aluminum channel stock.  I started with just the upright part of the spool holder.  Then, the spool spun a bit too easily, and it would unspool and catch on things.  The angled portion holds a dry sponge with a hole in it.  This has the dual purpose of wiping the dust off of the filament and providing a small amount of friction.

The reprap is all finished.

The reprap is all finished.

The green adapters on the spool ends are just bearing holders that help the spool turn more easily.  It was the first thing that I printed.  Here’s a very short video of it working:

 The final issue I had was with the GFCI circuit in my office.  I can’t figure out why I have GFCI there, but I do.  To add insult to injury, my firewall/router/server is on the same circuit.  So, every time the printer trips my GFCI, it takes down the internet and generally causes havoc.  I pulled my hair out over this one.  I replaced my (very expensive) GFCI circuit breaker and the printers power supply.

Trying to measure GFCI current

Trying to measure GFCI current

In the photo above, I’m trying to measure the peak ground current from the printer.  The fluke is on the mA setting with peak hold.  This is the highest reading I ever got, and the circuit didn’t trip.  It’s my understanding that GFCI trips when there’s about 30mA on the ground circuit.  My assumption at this point was that the shunt resistance in the DMM was limiting the peak current, therefore no 30mA spike and no trip.

The problem persisted for sometime, and I began to suspect the GFCI breaker.  I went to an electrician store, and the guy said that they can wear out.  After I replaced the circuit breaker, and $50 later, the problem got worse!  It would trip even when the printer wasn’t plugged in!  At least then, it was no longer an intermittent fault.  Now that I could reliably cause the fault, I at least had hope for isolating it.  I unplugged everything on the circuit and plugged in things one-by-one.  I turned out that a cheap power strip (the same kind as in the above photo) was the culprit.  Boooo.

Any way, I’m now a 3D printing convert.  But I promise I won’t be annoying about it. 🙂

, , , , ,

No Comments

Emma’s Red Dresser

Katie and I needed to get a dresser/changing table for Emma.  We decided to find an antique dresser to redo rather than the pressed-wood pieces of crap you can buy today.  We found one at the Corvallis ARC that fit the bill nicely.  Unfortunately, I neglected to take photos of it before attacking it with the sander.  The following two photos are during the sanding process, though.

Starting to sand off the stain

Starting to sand off the stain

Some of the drawers before sanding

Some of the drawers before sanding

The stain and finish that they used was nasty to sand off.  When it got hot from the friction, it would melt, kinda, and gum up the sand paper.  Eventually, and after many sheets, we got it all off.  In the process, I bought a Ryobi Corner Cat which I like O.K.  I had to replace the velcro pad that holds the sand paper because it wore out.  Shipping took a bit, but the replacements were only a dollar or two.

Once I got all the stain off, I could assess the level of wear the dresser had accumulated over the years.  In total, it wasn’t bad.  It was pretty interesting to see how construction methods have changes over the years.

Slightly distressed corner

Slightly distressed corner

In getting ready to paint, I masked off the inside of the chest openings.  In this view, you can see the construction.  Lots of random sizes of lumber, everything is mortised, etc.

ready to paint the chest

ready to paint the chest

It took a ton of coats to adequately paint the dresser.  It didn’t help that we did this at the height of summer, and it was HOT.  The paint was practically drying as soon as it left the pail.  This left a very poor finish, and honestly, I’m a bit disappointed in it.

The chest is painted

The chest is painted

Eventually, it got to a point that I could live with, and we reassembled everything.  I chucked the knobs into the drill to sand the finish off.  I’d like to eventually get some antique porcelain knobs.  I think that would look really nice.

One extra thing we had to do, that I don’t have pictures of, is replace the drawer bottoms.  Most of them were in really bad shape, and weren’t even square!  I just bought some plywood at the store and had my friend Tom cut them to size on his table saw.

Painting and reassembling all finished

Painting and reassembling all finished

We’re all finished!  Here’s the dresser in its new home, complete with changing pad.  Hopefully, as Emma grows up, she’ll like and appreciate it!

, , , , , , , , ,

No Comments

Support for the Rafael Micro R820t tuner in Cocoa Radio

R820t tuner on a rtl-sdr compatible dongle, from eBay seller CosyCave

Relating to the rtl-sdr work that has been done, the E4000 tuner was the standard barer for a long time.  However, Elonics has discontinued this part, and it’s becoming difficult to find.  The popularity, and scarcity, of this part has encouraged sellers to offer products claiming to be built with the E4000 and are not.  Luckily, someone discovered the code for using the R820t tuner in the Linux V4Lin drivers.  They ported this code into the rtl-sdr source maintained by osmocom.

I just finished porting their code into Cocoa Radio.  Now, it’s possible to use my software with both the E4000 and the R820t.  On startup, Cocoa Radio will automatically detect which tuner you’re using and perform the appropriate actions.

It did take a little while to finish this work, and there are several more tuners out there.  If you are desperate for support of a specific tuner, you can donate a device for the cause and I’ll try to support it.  By the way, Softshell uses the same code for tuning as Cocoa Radio, if you recompile softshell, it should include this new code.

All the relevant code and binaries are, as usual, available at github.  Make absolutely sure that you also update the softshell repository!

, , , , ,

3 Comments

New Cocoa Radio release!!

Cocoa radio interface explained (click for full size)

Well, I’m back from vacation and I want to tell everyone about a new version of Cocoa Radio (my application for demodulating radio signals using the rtlsdr dongles on mac os x, written in Objective C).  This version seems to be running really well.  I’ve set the sample rate to 1024000 samples per second for the moment (though this value can be changed in the code), and at this rate everything seems really stable.  Please give it a try and create issues at the github issues page if you find any problems.  I should say that I’m a little tired of working on it, so unless there are major issues I’ll be working on other projects for a while.  I encourage others to take a look at the code if they’re interested in SDR.  It’s not as scary as it looks!

Also, the sliders are a little buggy (especially the bandwidth ones).  Move the a little bit once the app starts up and they’ll work correctly.

Finally, I don’t have any support for AM (amplitude modulation) yet.  It’s an easy modulation type, and I may add it soon.

, , , , , ,

12 Comments

Softrock application available

Here’s a compiled executable, including the rtl-sdr library, for those that don’t want to get the source on github and compile it.

Also, if anyone wants to design a logo, it would be much appreciated!

Softshell-alpha

, , , ,

2 Comments